Abstract
The purpose of this study is to evaluate the glenohumeral contact area, center of glenohumeral contact area, and center of humeral head during simulated pitching motion in collegiate baseball pitchers using four-dimensional computed tomography (4D CT). We obtained 4D CT data from the dominant and non-dominant shoulders of eight collegiate baseball pitchers during the cocking motion. CT image data of each joint were reconstructed using a 3D reconstruction software package. The glenohumeral contact area, center of glenohumeral contact area, center of humeral head, and oblateness of humeral head were calculated from 3D bone models using customized software. The center of glenohumeral contact area translated significantly from anterior to posterior during maximum external rotation to maximum internal rotation. The center of humeral head translated from posterior to anterior during maximum external rotation to maximum internal rotation. There was a high negative correlation between anterior translation of the center of glenohumeral contact area and center of humeral head, and a positive correlation between the translation and the oblateness. 4D CT analyses demonstrated that the center of humeral head translated in the opposite direction to that of the center of glenohumeral contact area during external rotation to internal rotation in abduction in the dominant and non-dominant shoulders. This diametric translation can be explained by the oblateness of the humeral head. 4D CT scanning and the software for bone surface modeling of the glenohumeral joint enabled quantitative assessment of glenohumeral micromotion and identified humeral head oblateness as the cause of diametric change.
CT scanning protocol in washin/washout method to reduce the effect of xenoninduced flow activation on xenon-enhanced computed tomography calculations: cerebral blood flow and partition coefficient